A foot flexion device, when applied to the foot or feet of a patient, stimulates circulation and provides physiotherapy. Preferably, the device dorsiflexes the patient's foot or feet, that is, it rotates the foot about the ankle joint in a natural motion to thereby move the toes of the foot toward and away from the patient's knee, which in turn exercises the muscles of the foot, ankle and calf to thus achieve enhanced circulation of blood and lymph in the lower extremities and increased flexibility of the joints of the ankle and foot. By performing continuous passive flexion and extension of the muscles of the lower leg and feet, a foot flexion device provides therapy directed toward preventing both disease and atrophy in the lower extremities. Stimulation of the plantar portion of the foot can also aid in achieving these goals
In foot dorsiflexion devices, the toes of the foot are moved passively in an upward-downward reciprocating motion. Foot dorsiflexion can be achieved by mechanically manipulating the sole and toe portion of the foot up/down about the natural axis of rotation of the ankle joint located at the heel of the user's foot.
Foot dorsiflexion is useful to treat individuals having decreased circulation. For example, temporarily immobilized or paralyzed persons no longer utilize the muscles of the lower leg to help pump the blood in the venous circulation back to the heart. The resultant venous blood stasis predisposes such individuals to abnormal clot formation in the legs, a condition commonly referred to as deep venous thrombosis ("DVT"). DVT is widespread, being a major complication of many surgical procedures, stroke, coma, spinal cord injury, therapeutic drug treatments and many other medical conditions. DVT is also quite common in those individuals who are bedridden or confined to wheelchairs.
Another condition which includes the symptom of blood and fluids pooling in the lower extremities is known as dependant edema. In dependant edema, otherwise healthy people experience such fluid pooling when their lower legs and feet hang for an extended period, for example, such as when they are sitting in an airplane or automobile seat, or when seated watching television. Dependant edema, which is common in people having varicose veins, can lead to DVT and all of its complications.
The repetitive contraction and relaxation of the muscles of the foot and calf as, for example, in walking, is well known to enhance blood flow. Mechanical manipulation provided by a flexion device provides similar motion to the muscles of the foot and calf and thereby prevents the pooling of blood in the venous vasculature of the lower extremities. Thus, by enhancing blood and lymph flow, the repetitive exercising or manipulation of the muscles of the foot and calf very significantly reduces the risk of DVT, a potentially lifethreatening medical condition.
Passive flexion/extension also enhances blood flow in individuals with peripheral vascular disease ("PVD"), a deteriorating condition characterized by chronically diseased or partially obstructed vasculature of the extremities. PVD has a high morbidity rate and is widespread. PVD is frequently associated with chronic alcoholism, excessive use of tobacco products, advanced diabetic states, and other diseases and conditions of the circulatory system. Gangrene and eventual amputation of all or part of an affected extremity is commonly a result of untreated or poorly treated PVD.
Thus, preventive uses of foot flexion devices include those listed above as well as, for example, preventing edema and varicosities in the surface veins in the lower extremities. Additional uses relate to surgical procedures where a patient may be immobilized for hours at a time and to other conditions where a patient's leg or legs are not being used for extended periods of time.
Traditionally, the means of improving venous blood flow or decreasing blood clotting include medications and a variety of compression devices. The uses of medications are limited, however, by systemic side effects such as uncontrolled or internal bleeding. Known compression devices include elastic compression stockings, graduated and sequential compression stockings and foot compression devices such as those made under the brand name Medi-Strumph or by the Kendall Corporation of Mansfield, Massachusetts or the Jobst Corporation of Toledo, Ohio.
Use of compression devices is cumbersome, however, since the care provider must first fit or adapt the device to the varying size and shape of the patient's limb. Furthermore, the difficulty encountered by a user in applying the devices to the limb often results in discomfort and associated decreased patient compliance. An even more serious disadvantage to such devices are the potential detrimental effects of direct compression to the arterial vasculature in patients with PVD. For these reasons, other means of preventing DVT, such as mechanical manipulators of the lower extremities, have been developed.
Mechanical devices for manipulation of the foot are well known in the exercise, medical and physical therapy fields. For example, U.S. Pat. No. 4,842,265, to Kirk discloses an apparatus for the therapeutic manipulation of a person's feet. The device of Kirk is large and cumbersome, however, and must be strapped to the foot of a bed or to a table in order to function on a patient who is substantially in a supine position. U.S. Pat. No. 3,695,255, to Rodgers et al., and U.S. Pat. No. 3,370,584 to Girten disclose devices which can produce either simultaneous or alternating dorsiflexing of a patient's feet. Devices to simultaneously manipulate the foot and massage the calf are known, as well, including U.S. Pat. No. 4,003,374, to Mizrachy and U.S. Pat. No. 4,795,148 to Rangaswamy. All of these devices suffer from one or more shortcomings, however.
For example, a foot flexion device, such as that shown in U.S. Pat. No. 4,842,265, to Kirk, disadvantageously restricts the mobility of the wearer to a lying-down position. Such a supine position is dangerous to certain patients, even when temporary in duration, since it can compromise the patient's blood and lymph circulation. Furthermore, prolonged supine positioning associated with such a device increases the incidence of bed sores, skin breakdown and necrosis. Furthermore, even where the risks of decreased arterial circulation are small, it is inconvenient for the patient to maintain a supine position. Inconvenience results in lower patient compliance and the concomitant continuation of the disease state or condition.
In addition, current foot flexion devices can be dangerous because they lack a safe way to prevent excessive or inappropriate flexion of the foot. In certain situations, such as when the patient's calf muscle goes into a spasm, tremors or tetany, or when a user voluntarily attempts to move a foot in opposition to the motion of the invention, a continuous-mode Foot flexion device can injure the muscle tissue or joints because of excessive machinegenerated flexion. Although such devices are equipped with a manual shut off, the period of time between onset of a patient's muscle spasm and the shutoff of the device by the patient is oftentimes sufficient for injury or pain to occur. Moreover, when a user of such a device is sleeping, comatose or otherwise not consciously responsive, the time between the beginning of a period of excessive or inappropriate flexion and the shutoff of the flexion device is even longer.
Thus, there is a need in the medical and health care fields for a foot flexion device which requires a minimum of attendance, is effective in all conditions requiring enhanced blood flow in the lower extremities, does not restrict patient movement, is portable, is easy to apply and use, has safety features which automatically engage to thereby prevent pain and injury to the user, and which provides controllability with respect to 1) the range or extent of flexion, 2) the rate of flexion, and 3) the amount of force applied to cause flexion. An additional need in the field is for a foot flexion device which can be used simultaneiusly in conjunction with other therapies.